Position Detecting Device Magnetic Path Material DC Flux Interference
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Solution Overview
Problem
Position detecting devices with magnetic path plates of high permeability interfere with geomagnetic sensors, causing incorrect orientation detection due to biasing of DC magnetic flux, and existing solutions compromise sensor sensitivity for electromagnetic coupling.
Innovation Solution
A position detecting device using a magnetic path material with controlled permeability to minimize interference with DC magnetic flux and a shield material to maintain electromagnetic coupling efficiency, comprising a mixture of high permeability materials with polymers to set desired permeability and electrical resistance, and a non-magnetic shield with conductivity to manage eddy currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a magnetic path plate with high permeability (e.g., amorphous metal) is used to enhance electromagnetic coupling and form a magnetic path for alternating magnetic fields, then the detection sensitivity of the position detecting device is improved, but DC magnetic flux (such as geomagnetism) is biased and interferes with geomagnetic sensors causing incorrect orientation detection
Solution Approach 1:
The magnetic path plate is divided into multiple independent magnetic path elements (particles) that are dispersed throughout the resin layer. This segmentation prevents the formation of continuous magnetic flux paths that would bias DC magnetic fields, while still providing localized magnetic guidance for alternating fields to enhance detection sensitivity.
Solution Approach 2:
The magnetic path elements are strategically positioned in specific regions where alternating magnetic field concentration is needed for position detection, rather than using a uniform magnetic path structure throughout. This allows local enhancement of electromagnetic coupling while maintaining overall transparency to DC magnetic fields.
2Power
If a magnetic path plate with high permeability is used to concentrate and guide alternating magnetic flux, then the electromagnetic coupling between the position detecting device and position indicator is enhanced, but eddy currents are generated that cause energy loss and reduce detection accuracy
Solution Approach 1:
The magnetic path plate is segmented into discrete magnetic particles dispersed in an insulating resin matrix. This segmentation interrupts continuous eddy current paths while maintaining magnetic flux guidance capabilities, thereby reducing eddy current losses while preserving electromagnetic coupling efficiency.
Solution Approach 2:
An insulating resin material is introduced as an intermediary between the magnetic path elements. This resin layer electrically isolates the magnetic particles from each other, preventing eddy current formation while allowing magnetic flux to pass through the magnetic particles for enhanced coupling.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Ensures accurate geomagnetic orientation detection while maintaining sensor sensitivity and preventing electromagnetic field leakage, by allowing DC magnetic flux transmission without bias and enhancing the magnetic path for alternating fields.
Implementation Method 1
a magnetic path material with controlled permeability to minimize interference with DC magnetic flux and enhance the magnetic path for alternating fields
Implementation Method 2
a non-magnetic shield with conductivity to manage eddy currents
Implementation Method 3
a coil for generating an alternating magnetic field for electromagnetic coupling with the position indicator
Data Source
Figure 1
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Figure 4
AI summary
A position detecting device is disclosed for use with a position indicator. The position detecting device includes a coil substrate, a magnetic path material, and a shield material. A coil for generating an alternating magnetic field for electromagnetic coupling with the position indicator is disposed on the coil substrate. The magnetic path material is composed of a material having such permeability as not to disturb direct current magnetic flux but to form a magnetic path for the alternating magnetic field generated by the coil, and having predetermined electrical resistance for suppressing flow of an eddy current in order to enhance the material's performance as a magnetic path. The shield material is a non-magnetic substance that does not disturb the direct current magnetic flux due to the direct current magnetic field and that has electrical conductivity for generating an eddy current based on the alternating magnetic field.